Roaming/Switching Radios is controlled by the client, not the AP. > -----Original Message----- > From: Kuhl, Vince (DotComm) [mailto:[EMAIL PROTECTED] > Sent: Wednesday, September 22, 2004 9:11 AM > To: '[EMAIL PROTECTED]' > Subject: RE: [SOCALWUG] WLAN Design Question > > Thanks for the replies. Sorry I am not able to present a > clearer picture. > Some of our users jump from one radio to another, we are > using eap and the > logs show the re-auth/re-assoc occur on the new radio. When > this occurs the > user losses connectivity for their TN3270 session. I am not > confident in the > original network design and am looking for resources on > preventing users > from jumping from radio to radio. Should this be done on the > client side? > Also I understand the "1,6,11" channels are non-overlapping - > we attempted > to spread the frequencies out as much as possible using all > channels. If > this is the case, should you only use "1,6,11" > > -----Original Message----- > From: Jim Thompson [mailto:[EMAIL PROTECTED] > Sent: Tuesday, September 21, 2004 11:24 PM > To: [EMAIL PROTECTED] > Subject: Re: [SOCALWUG] WLAN Design Question > > > > In my (ahem) experience, many "experienced wireless LAN designer(s)" > have precious little theoretic base. They just "know what works". > > e.g. the oft-quoted (but inaccurate) 3 non-overlapping channels. > > Worse are those pretty picture of hexagons with each hexagon > representing the (idealized) coverage area of a single AP, > with adjacent > hexagons (APs) in different colors (representing different > frequencies), > promulgating the "1, 6, 11" arguement, and causing anywhere mild to > severe interference, no matter what load is applied to the network. > > It causes cognative dissonence when I say it, but the better > (dare I say > "correct") way to deploy multiple APs is to put them on the (you'll > hate this, I know) *same* channel. There are limits to this, > of course, > see below. At the very least, this makes the "hexagons" > somewhat larger. > > This allows 802.11's CSMA/CA to work. (If the preamble is > detected, CCA > gets set and the MAC holds off transmitting for the duration > of the packet.) > > Move off channel, and all the baseband can 'see' is more > noise (due to > the in-channel power of the STA (or AP) operating on an > adjacent channel). > > If the operation of an adjacent (or alternate) channel STA > (all APs are > STAs, btw) is such that the local receiver can't decode the preamble > (which is sent at the lowest modulation) then you're probably safe > moving to the next adjacent (or better, alternate) channel. > Thus, the > distance between the centers of the hexagons should be about the > distance at which you can maintain (for 11b) 1Mbps connectivity. > > Still worse are the people who attempt to engineer large coverage via > high-gain omnis on a set of APs. This actually makes the > problem worse > (and I can prove it, the math is simple). > > jim > > Jack Unger wrote: > > Get help from an experienced wireless LAN designer. You > likely have too > > many access points located too close together. Under > normal-use traffic > > loads, you will have an unacceptably high level of > self-interference > > (too many packets colliding with each other). The result > will be slow > > throughput. > > jack > > > > > > Kuhl, Vince (DotComm) wrote: > > > >> I was looking for some resources on wlan design. I have a 6 story > >> building > >> with approx 5 radios per floor. All radio's are in the > same SSID. The > >> idea > >> was to provide redundancy for the users but most pc's only get an > >> acceptable > >> signal from one radio anyway. It seems as if this one large SSID > >> approach is > >> causing more of an interference problem than anything > else. Would it be > >> better to break the building up into separate SSID's? Any > thoughts or > >> resources would be appreciated. > >> Thanks > >> > > > > > --- > Incoming mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.760 / Virus Database: 509 - Release Date: 9/10/2004 > >
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